If the NSA hacks telecom infrastructure worldwide it is because it wants to get the information without having to go through court to get it and because it thinks this is more effective and faster. The latter is more evident than the first because you won't be able to present this information in court (although many of the presumed terrorists are now killed by Drones before they ever get to see a real court).
But this poses some big problems and can also create diplomatic and other difficulties even if the different intelligence agencies need information from the NSA to be able to re-act fast enough to dangers yet unknown to them. So they are like two scorpions in a bottle who will only get out if they help each other out.
This is only possible if there is an European agreement that a number of people or organisations can be tracked and monitored throughout the European Union without having to present an individual court order in each of these countries. We already have Europol that can coordinate this and it needs the necessary supervision.
The only problem here is mission creep and the only way to stop mission creep is that the list may for example be never bigger than 100. This means that there is no way this system can be turned into a global surveillance tool but that is fast and general only for the most important terrorist suspects or contacts that need to be followed anywhere. The terror watchlist of nearly half a million people is a perfect example of this.
It is by going after the real leaders and organizers one by one that one can limit the operational possibilities of a terrorist organisation because they can't be replaced as easily as another disgruntled fighter taking up the gun or bomb of his fallen comrade in arms. And to do that you need the top100 tracklist throughout the US, Europe and the partners.
Nobody seriously has a problem with tracking the most dangerous terrorists but many people have a problem with the fact that some want to watch everybody all the time as if they all can turn into a terrorist one day.
And if the intelligence agencies have an instrument by which they can concentrate their resources on immediate dangers and the biggest organizers they can submit court orders for all the rest if they still need it.